Abstract
This study proposes two methods of optical watermarking based on multiplexed time-varying signals for computational ghost imaging using the Hadamard matrices. The proposed methods can realize image fusion and dual optical encryption. The time-varying signal is encoded into a specific Hadamard coefficient in advance and hidden in the light source of the transmitting end as a multiplicative factor or loaded at the receiving end as an additive factor. Theory and experiments confirm the feasibility of this scheme. Moreover, the scheme is highly scalable and has potential applications in multispectral single-pixel imaging.
Highlights
Ghost imaging (GI) [1,2,3] is a nonlocal imaging method
Many improvements have been made to the basic GI algorithm to recover images [28,29,30,31,32,33], such as differential GI [28], normalized GI (NGI) [29], corresponding imaging [30], pseudoreverse GI [31], sinusoidal GI [32], and GI using the Hadamard basis [33]. ese enhancements were mainly established to ensure that the reference beam of the optical path of the GI system effectively eliminates the influence of light source volatility using differential or normalized GI schemes. us, this study focuses on computational GI (CGI) with only one arm, and the corresponding algorithms are based on this scenario
The signal generated by the digital micromirror devices (DMDs) at the start of mask patterns display synchronizes the output signal of the digital-to-analog converter (DAC). e signal of the DAC can be hidden into the light source as a multiplicative factor at the transmitting end, or it can be placed as an additive factor at the receiving end, that is, directly connected to the DAQ (National Instruments, PCI-6220) in parallel with the signal collected using the PD. e collected composite signals are used for data processing and image reconstruction on the host computer
Summary
Ghost imaging (GI) [1,2,3] is a nonlocal imaging method. In particular, the object is illuminated by structural light, and the image is collected using a detector without a spatial resolution. GI has been used in various frequency bands [4,5,6,7,8] and is beneficial [8] at certain nonvisible wavelength ranges This technology has been used in the fields of microscopy [8], remote sensing [9, 10], threedimensional (3D) imaging [11, 12], multispectral imaging [13], imaging through complex media [14, 15], tomography [16, 17], optical encryption [18,19,20,21], solving image distortion caused by uneven spatial distribution [22], and introduction calculation time [23]. This system is highly scalable and can be transplanted into Fourier or multispectral single-pixel imaging, as proposed earlier
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